This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-336422, filed Nov. 26, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a stacked display device and, more particularly, to a stacked display device constructed by one intermediate substrate and one outer substrate which sandwiches the intermediate substrate.
As electrooptic display devices using, e.g., a liquid crystal panel, a composite-type device having a touch input panel stacked on the front surface of a display panel on the observation side and a two-layered device having two, front and rear display panels are stacked are conventionally known. These devices are called stacked display devices.
FIG. 1 is a sectional view of a conventional stacked display device in which hatching is omitted. FIG. 1 shows a composite-type display device having a touch input panel (to be referred to as a touch panel hereinafter) 2 stacked on the front surface of a liquid crystal display panel 1.
In this stacked display device, one intermediate substrate 10 is shared as substrates on the adjacent sides of the liquid crystal display panel 1 and touch panel 2. This device comprises the intermediate substrate 10, a display panel substrate 11 opposing the rear surface of the intermediate substrate 10, and a touch panel substrate 12 opposing the front surface of the intermediate substrate 10.
The intermediate substrate 10 and display panel substrate 11 are transparent substrates made of glass. Transparent display panel electrodes 13 and 14 opposing each other are formed on the rear surface of the intermediate substrate 10 and on the inner surface (surface opposing the intermediate substrate 10) of the display panel substrate 11, respectively. Alignment films 15 and 16 cover the electrodes 13 and 14, respectively.
One of the intermediate substrate 10 and display panel substrate 11, and for example, the display panel substrate 11 has, on one end side, an edge portion projecting from the intermediate substrate 10 as the other substrate. The edge portion has, on its inner surface, a plurality of display panel terminal electrodes 17 corresponding to the display panel electrodes 13 and 14 formed on the rear surface of the intermediate substrate 10 and on the inner surface of the display panel substrate 11, respectively.
Although not illustrated in FIG. 1, the inner surface of the display panel substrate 11 has lead wires which connect the display panel electrodes 14 formed on the inner surface of the display panel substrate 11 to predetermined terminal electrodes of the plurality of display panel terminal electrodes 17 formed at the edge portion, pad electrodes corresponding to the terminal connections of the display panel electrodes 13 formed on the rear surface of the intermediate substrate 10, and lead wires which connect the pad electrodes to the remaining predetermined terminal electrodes of the plurality of display panel terminal electrodes 17.
The intermediate substrate 10 and display panel substrate 11 are jointed by a first frame-shaped sealing member 18 inserted therebetween while maintaining a predetermined gap. The terminal connections of the display panel electrodes 13 formed on the rear surface of the intermediate substrate 10 and the above-described pad electrodes on the inner surface of the display panel substrate 11 are electrically connected through conductive members (not shown) in or near the substrate joint region by the sealing member 18. A liquid crystal is encapsulated in the region in the gap, surrounded by the sealing member 18 between the intermediate substrate 10 and the display panel substrate 11 to form a liquid crystal layer 19. The liquid crystal display panel 1 has the above-described structure.
The touch panel substrate 12 opposing the front surface of the intermediate substrate 10 is formed from a transparent resin film having flexibility. Transparent touch panel electrodes 20 and 21 are formed on the front surface of the intermediate substrate 10 and the inner surface (surface opposing the intermediate substrate 10) of the touch panel substrate 12 made of a resin film, respectively, so as to extend in directions perpendicular to each other.
One of the intermediate substrate 10 and touch panel film substrate 12, and for example, the intermediate substrate 10 has, on one end side, an edge portion projecting from the film substrate 12 as the other substrate. The edge portion has, on its front surface, a plurality of touch panel terminal electrodes 22 corresponding to the touch panel electrodes 20 and 21 formed on the front surface of the intermediate substrate 10 and the inner surface of the film substrate 12, respectively.
Although not illustrated in FIG. 1, the front surface of the intermediate substrate 10 has lead wires which connect the touch panel electrodes 20 formed on the front surface of the intermediate substrate 10 to predetermined terminal electrodes of the plurality of touch panel terminal electrodes 22 formed at the edge portion, pad electrodes corresponding to the terminal connections of the touch panel electrodes 21 formed on the inner surface of the film substrate 12, and lead wires which connect the pad electrodes to the remaining predetermined terminal electrodes of the plurality of touch panel terminal electrodes 22.
The touch panel 2 is constituted by jointing the intermediate substrate 10 and the touch panel film substrate 12 with a second frame-shaped sealing member 23 inserted therebetween and electrically connecting the terminal connections of the touch panel electrodes 21 formed on the inner surface of the touch panel substrate 12 to the pad electrodes on the front surface of the intermediate substrate 10 through conductive members (not shown) in or near the substrate joint region by the frame-shaped sealing member 23.
This stacked display device is a TN (Twisted Nematic) type liquid crystal display device, for which the initial aligned state of the liquid crystal molecules in the liquid crystal layer 19 of the liquid crystal display panel 1 is twisted alignment with a predetermined twist angle (e.g., almost 90xc2x0), and polarizing plates 24 and 25 are arranged on the rear surface of the liquid crystal display panel 1 (outer surface of the display panel substrate 11) and the front surface of the touch panel 2 (outer surface of the touch panel film substrate 12) while extending their transmission axes in predetermined directions.
The stacked display device shown in FIG. 1 has a composite combination with the touch panel 2 stacked on the front surface of the liquid crystal display panel 1. However, some stacked display devices have two display panels stacked on the front and rear sides. For example, in a two-stacked display device having two liquid crystal display panels stacked, conventionally, the touch panel 2 of the stacked display device shown in FIG. 1 is replaced with a second liquid crystal display panel.
However, as shown in FIG. 1, the conventional stacked display device has the intermediate substrate 10 shared as substrates on the adjacent sides of the first panel (liquid crystal display panel in FIG. 1) 1 and second panel (touch panel in FIG. 1) 2, the first panel substrate 11 opposing the rear surface of the intermediate substrate 10, and the second panel substrate 12 opposing the front surface of the intermediate substrate 10, in which the first panel electrodes 13 and 14 are formed on one surface of the intermediate substrate 10 and the inner surface of the first panel substrate 11, and the second panel electrodes 20 and 21 are formed on the other surface of the intermediate substrate 10 and the inner surface of the second panel substrate 12. For this reason, three substrates, i.e., the intermediate substrate 10, first panel substrate 11, and second panel substrate 12 must be manufactured. This results in an increase in the number of manufacturing processes and an increase in manufacturing cost.
Additionally, in the conventional stacked display device, since the terminal electrodes 17 of the first panel 1 are formed at the edge portion of one of the intermediate substrate 10 and first panel substrate 11 (first panel substrate 11 in FIG. 1), and the terminal electrodes 22 of the second panel 2 are formed at the edge portion of one of the intermediate substrate 10 and second panel substrate 12 (intermediate substrate 10 in FIG. 1), the driving circuit for the first panel, which is connected to the terminal electrodes 17 of the first panel 1, and that for the second panel, which is connected to the terminal electrodes 22 of the second panel 2, must be connected in separate processes. Hence, the electrical connection operation in mounting this stacked display device in an electronic device is cumbersome, resulting in an increase in mounting labor.
It is an object of the present invention to provide a stacked display device which decreases the number of substrates to be used, can easily be manufactured at low cost by a small number of manufacturing processes, and is convenient for wiring connection to an external circuit.
In order to achieve the above object, according to the present invention, there is provided a stacked display device comprising:
one first substrate having electrodes formed on both of a front surface and a rear surface;
one second substrate having a one-end-side portion opposing the front surface of the first substrate and the other-end-side portion opposing the rear surface of the first substrate, the second substrate having a first panel electrode assembly opposing the electrodes formed on the front surface of the first substrate, a second panel electrode assembly opposing the electrodes formed on the rear surface of the first substrate, and a plurality of terminal electrodes electrically connected to the first panel electrode assembly and/or the second panel electrode assembly;
a first connecting member which connects the first substrate and the one-end-side portion of the second substrate to construct a first panel;
a second connecting member which connects the first substrate and the other-end-side portion of the second substrate to construct a second panel; and
an electrooptic substance layer having an electrooptic effect and formed between the first substrate and the second substrate at least in one of the first panel and second panel.
According to this stacked display device, since one substrate is formed into a substantially U-shape, and another substrate is disposed in the opposite portions of the substrate to form a stacked display device having two panels stacked, the number of substrates can be two, i.e., smaller than three for the prior-art device. In addition, electrodes for the two panels can be formed together on the substrate having the U shape. Hence, the number of processes and labor in manufacturing the stacked display device largely decrease to considerably reduce the manufacturing cost.
Furthermore, since the first panel electrode assembly and second panel electrode assembly are formed together on one substrate, terminal electrodes to be connected to these electrode assemblies can be arranged together at one portion, and wiring connection to an external circuit in mounting the device in an electronic device is very easy.
In the above stacked display device, the second substrate preferably comprises a flexible film substrate that can be bent at a predetermined portion to sandwich the first substrate while causing both side portions to oppose the two surfaces of the first substrate. When the edge portion on one side of the second substrate projects from the first substrate, and the terminal electrodes connected to the first panel electrode assembly and those connected to the second panel electrode assembly are arranged together at the projecting edge portion, wiring connection to an external circuit such as a driving circuit is facilitated.
In the above stacked display device, the first panel electrode assembly comprises first panel electrodes opposing the electrodes formed on the front surface of the first substrate, and wiring members for connecting the first panel electrodes to corresponding electrodes of the terminal electrodes. In this case, preferably, the front surface of the first substrate has a plurality of terminal connections connected to the electrodes on the front surface, and the first panel electrode assembly comprises a plurality of pad electrodes correspondingly connected to the plurality of terminal connections on the first substrate, respectively, and wiring members for connecting the pad electrodes to corresponding electrodes of the terminal electrodes. Thus, the terminal electrodes corresponding to the electrodes opposing the first panel electrodes, which are formed on the first substrate, can also be arranged together at the predetermined edge portion of the second substrate, and connection to an external circuit in mounting is further facilitated.
In the above stacked display device, the second panel electrode assembly comprises second panel electrodes opposing the electrodes formed on the rear surface of the first substrate, and wiring members for connecting the second panel electrodes to corresponding electrodes of the terminal electrodes. In this case, the rear surface of the first substrate has a plurality of terminal connections connected to the electrodes on the rear surface, and the second panel electrode assembly comprises a plurality of pad electrodes correspondingly connected to the plurality of terminal connections formed on the first substrate, respectively, and wiring members for connecting the pad electrodes to corresponding electrodes of the terminal electrodes. Thus, the terminal electrodes corresponding to the electrodes on the first substrate, which oppose the second panel electrodes, can also be arranged together at the predetermined edge portion of the second substrate, and connection to an external circuit in mounting is further facilitated.
In the above stacked display device, preferably, one of the first and second panels comprises a display panel having the electrooptic substance layer formed between the first and second substrates, and the other panel comprises a touch input panel. A liquid crystal is preferable for the electrooptic substance layer in that case.
In the above stacked display device, both of the first and second panels may comprise display panels each having the electrooptic substance layer formed between the first and second substrates. A liquid crystal is preferable as the electrooptic substance layer in that case as well.
The above-described object of the present invention can also be achieved by a stacked display device comprising:
one intermediate substrate having electrodes formed on both of a front surface and a rear surface;
one flexible substrate bent at a predetermined portion and sandwiching the intermediate substrate with a one-end-side portion from the bent portion opposing the front surface of the intermediate substrate and the other-end-side portion from the bent portion opposing the rear surface of the intermediate substrate, one of the side portions having an edge portion projecting from the intermediate substrate, the flexible substrate having a first panel electrode assembly opposing the electrodes formed on the front surface of the intermediate substrate, a second panel electrode assembly opposing the electrodes formed on the rear surface of the intermediate substrate, and a plurality of terminal electrodes formed at the projecting edge portion and electrically connected to the first panel electrode assembly and/or the second panel electrode assembly;
a first connecting member which connects the intermediate substrate and the one-end-side portion of the film substrate to construct a first panel;
a second connecting member which connects the intermediate substrate and the other-end-side portion of the film substrate to construct a second panel; and
an electrooptic substance layer having an electrooptic effect and formed between the intermediate substrate and the film substrate at least in one of the first and second panels.
According to this stacked display device, one flexible substrate is bent to two side portions, and another substrate is disposed between the side portions to form a stacked display device having two panels stacked. For this reason, the number of substrates can be as small as two, and the stacked display device can easily be manufactured only by bending one flexible substrate. In addition, electrodes of the two panels can be formed together on one flexible substrate. Hence, the number of processes and labor in manufacturing the stacked display device decrease to greatly reduce the manufacturing cost.
In the above stacked display device, the first panel electrode assembly preferably comprises a plurality of first panel electrodes opposing the electrodes formed on the front surface of the intermediate substrate, and a plurality of wiring members for connecting the first panel electrodes to corresponding electrodes of the terminal electrodes. In this case, preferably, the front surface of the intermediate substrate has a plurality of terminal connections connected to the electrodes on the front surface, and the first panel electrode assembly formed on the flexible substrate comprises a plurality of pad electrodes correspondingly connected to the plurality of terminal connections, respectively, and wiring members for connecting the pad electrodes to corresponding electrodes of the terminal electrodes.
In the above stacked display device, the second panel electrode assembly preferably comprises a plurality of second panel electrodes opposing the electrodes formed on the rear surface of the intermediate substrate, and a plurality of wiring members for connecting the second panel electrodes to corresponding terminal electrodes. In this case, preferably, the rear surface of the intermediate substrate has a plurality of terminal connections connected to the electrodes on the rear surface, and the second panel electrode assembly formed on the flexible substrate comprises a plurality of pad electrodes correspondingly connected to the plurality of terminal connections formed on the intermediate substrate, respectively, and wiring members for connecting the pad electrodes to corresponding electrodes of the terminal electrodes.
In the above stacked display device, preferably, one of the first and second panels comprises a display panel having the electrooptic substance layer formed between the intermediate substrate and the flexible substrate, and the other panel comprises a touch input panel.
In the above stacked display device, both of the first and second panels may comprise display panels each having the electrooptic substance layer formed between the intermediate substrate and the flexible substrate.
The above object of the present invention can also be achieved by a stacked display device constructed by stacking a first panel and a second panel, comprising one intermediate substrate, one outer substrate having a one-end-side portion opposing front surface of the intermediate substrate and the other-end-side portion opposing the rear surface of the intermediate substrate, a plurality of terminal electrodes formed at an edge portion on one side of the outer substrate, a first panel electrode assembly formed on the front surface of the intermediate substrate and on an inner surface of the one-end-side portion of the outer substrate while making at least some parts oppose each other and connected to predetermined terminal electrodes of the plurality of terminal electrodes, a second panel electrode assembly formed on the rear surface of the intermediate substrate and on an inner surface of the other-end-side portion of the outer substrate while making at least some parts oppose each other and connected to the remaining terminal electrodes of the plurality of terminal electrodes, a first joint member which joints the intermediate substrate and the one-end-side portion of the outer substrate to construct the first panel, a second joint member which joints the intermediate substrate and the other-end-side portion of the outer substrate to construct the second panel, and an electrooptic substance layer having an electrooptic effect and formed between the intermediate substrate and the outer substrate at least in one of the first and second panels.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.